Neonatale jaundice hyperbilirubinemia(also known as Neonatal jaundice or neonatal hyperbilirubinemia, or neonatal icterus from the Greek word ἴκτερος), attributive adjective: icteric, is a yellowing of the skin and other tissues of a newborn infant. A bilirubin level of more than 85 μmol/l (5 mg/dL) leads to a jaundiced appearance in neonates whereas in adults a level of 34 μmol/l (2 mg/dL) is needed for this to occur. In newborns, jaundice is detected by blanching the skin with pressure applied by a finger so that it reveals underlying skin and subcutaneous tissue. Jaundiced newborns have yellow discoloration of the white part of the eye, and yellowing of the face, extending down onto the chest.
Neonatal jaundice can make the newborn sleepy and interfere with feeding. Extreme jaundice can cause permanent brain damage from kernicterus.
In neonates, the yellow discoloration of the skin is first noted in the face and as the bilirubin level rises proceeds caudal to the trunk and then to the extremities. This condition is common in newborns affecting over half (50–60%) of all babies in the first week of life.
Infants whose palms and soles are yellow, have serum bilirubin level over 255 μmol/l (15 mg/dL) (more serious level). Studies have shown that trained examiners assessment of levels of jaundice show moderate agreement with icterometer bilirubin measurements. In infants, jaundice can be measured using invasive or non-invasive methods.
- Progressive jaundice
This method is less accurate and more subjective in estimating jaundice.
Ingram icterometer: In this method a piece of transparent plastic known as Ingram icterometer is used. Ingram icterometer is painted in five transverse strips of graded yellow lines. The instrument is pressed against the nose and the yellow colour of the blanched skin is matched with the graded yellow lines and bilirubin level is assigned.
Transcutaneous bilirubinometer: This is hand held, portable and rechargeable but expensive and sophisticated. When pressure is applied to the photoprobe, a xenon tube generates a strobe light, and this light passes through the subcutaneous tissue. The reflected light returns through the second fiber optic bundle to the spectrophotometric module. The intensity of the yellow color in this light, after correcting for the hemoglobin, is measured and instantly displayed in arbitrary units.
Any of the following features characterizes pathological jaundice:
- Clinical jaundice appearing in the first 24 hours or greater than 14 days of life.
- Increases in the level of total bilirubin by more than 8.5 μmol/l (0.5 mg/dL) per hour or (85 μmol/l) 5 mg/dL per 24 hours.
- Total bilirubin more than 331.5 μmol/l (19.5 mg/dL) (hyperbilirubinemia).
- Direct bilirubin more than 34 μmol/l (2.0 mg/dL).
The aim of clinical assessment is to distinguish physiological from pathological jaundice. The signs which help to differentiate pathological jaundice of neonates from physiological jaundice of neonates are the presence of intrauterine growth restriction, stigma of intrauterine infections (e.g. cataracts, small head, and enlargement of the liver and spleen), cephalohematoma, bruising, signs of bleeding in the brain's ventricles. History of illness is noteworthy. Family history of jaundice and anemia, family history of neonatal or early infant death due to liver disease, maternal illness suggestive of viral infection (fever, rash or lymphadenopathy), maternal drugs (e.g. sulphonamides, anti-malarials causing red blood cell destruction in G6PD deficiency) are suggestive of pathological jaundice in neonates
The bilirubin levels for initiative of phototherapy varies depends on the age and health status of the newborn. However, any newborn with a total serum bilirubin greater than 359 μmol/l ( 21 mg/dL) should receive phototherapy.
Phenobarbital is used to treat neonatal jaundice by increasing liver metabolism and thus lowering bilirubin levels. In the 1950s, phototherapy was discovered, and became the standard treatment, however phenobarbital therapy is still in common use when access to phototherapy is inconvenient or impractical. One striking benefit of successful phenobarbital therapy is the rapid onset of recovery.
The use of phototherapy was first discovered, accidentally, at Rochford Hospital in Essex, England. The ward sister (nurse) of the premature baby unit firmly believed that the infants under her care benefited from fresh air and sunlight in the courtyard. Although this led to the first noticing of jaundice being improved with sunlight, further studies only progressed when a vial of blood sent for bilirubin measurement sat on a windowsill in the lab for several hours. The results indicated a much lower level of bilirubin than expected based on the patient's visible jaundice. Further investigation led to the determination that blue light, wavelength of 420-480 nm (peak 458 nm), caused transformation of the trans bilirubin to cis bilirubin, a soluble product that does not contribute to kernicterus. Although some pediatricians began using phototherapy in the United Kingdom following Dr. Cremer's publishing the above facts in the Lancet in 1958, most hospitals only began to regularly use phototherapy ten years later when an American group independently made the same discovery.
Infants with neonatal jaundice are treated with colored light called phototherapy. Physicians randomly assigned 66 infants 35 weeks of gestation to receive phototherapy. After 15±5 the levels of bilirubin, a yellowish bile pigment that in excessive amounts causes jaundice, were decreased down to 0.27±0.25 mg/dl/h in the blue light. This suggests that blue light therapy helps reduce high bilirubin levels that cause neonatal jaundice.
Exposing infants to high levels of colored light changes trans-bilirubin to the more water-soluble cis-form which is excreted in the bile. Scientists studied 616 capillary blood samples from jaundiced newborn infants. These samples were randomly divided into three groups. One group contained 133 samples and would receive phototherapy with blue light. Another group contained 202 samples would receive room light, or white light. The final group contained 215 samples, and were left in a dark room. The total bilirubin levels were checked at 0, 2, 4, 6, 24, and 48 hours. There was a significant decrease in bilirubin in the first group exposed to phototherapy after two hours, but no change occurred in the white light and dark room group. After 6 hours, there was a significant change in bilirubin level in the white light group but not the dark room group. It took 48 hours to record a change in the dark room group’s bilirubin level. Phototherapy is the most effective way of breaking down a neonate’s bilirubin.
Phototherapy works through a process of isomerization that changes trans-bilirubin into the water-soluble cis-bilirubin isomer.
In phototherapy, blue light is typically used because it is more effective at breaking down bilirubin (Amato, Inaebnit, 1991). Two matched groups of newborn infants with jaundice were exposed to intensive green or blue light phototherapy. The efficiency of the treatment was measured by the rate of decline of serum bilirubin, which in excessive amounts causes jaundice, concentration after 6, 12 and 24 hours of light exposure. A more rapid response was obtained using the blue lamps than the green lamps. However, a shorter phototherapy recovery period was noticed in babies exposed to the green lamps. Green light is not commonly used because exposure time must be longer to see dramatic results.
Ultraviolet light therapy may increase the risk of skin moles, in childhood. While an increased number of moles is related to an increased risk of skin cancer, it is not ultraviolet light that is used for treating neonatal jaundice. Rather, it is simply a specific frequency of blue light that does not carry these risks.
Increased feedings help move bilirubin through the neonate’s metabolic system.
The light can be applied with overhead lamps, which means that the baby's eyes need to be covered, or with a device called a Biliblanket, which sits under the baby's clothing close to its skin.
Much like with phototherapy the level at which exchange transfusion should occur depends on the health status and age of the newborn. It should however be used for any newborn with a total serum bilirubin of greater than 428 μmol/l ( 25 mg/dL ).